CN107430578B - Asynchronous interface - Google Patents
Asynchronous interface Download PDFInfo
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- CN107430578B CN107430578B CN201680017720.6A CN201680017720A CN107430578B CN 107430578 B CN107430578 B CN 107430578B CN 201680017720 A CN201680017720 A CN 201680017720A CN 107430578 B CN107430578 B CN 107430578B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/42—Bus transfer protocol, e.g. handshake; Synchronisation
- G06F13/4204—Bus transfer protocol, e.g. handshake; Synchronisation on a parallel bus
- G06F13/4208—Bus transfer protocol, e.g. handshake; Synchronisation on a parallel bus being a system bus, e.g. VME bus, Futurebus, Multibus
- G06F13/4213—Bus transfer protocol, e.g. handshake; Synchronisation on a parallel bus being a system bus, e.g. VME bus, Futurebus, Multibus with asynchronous protocol
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/42—Bus transfer protocol, e.g. handshake; Synchronisation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F5/00—Methods or arrangements for data conversion without changing the order or content of the data handled
- G06F5/06—Methods or arrangements for data conversion without changing the order or content of the data handled for changing the speed of data flow, i.e. speed regularising or timing, e.g. delay lines, FIFO buffers; over- or underrun control therefor
- G06F5/065—Partitioned buffers, e.g. allowing multiple independent queues, bidirectional FIFO's
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/40—Bus structure
- G06F13/4004—Coupling between buses
- G06F13/4027—Coupling between buses using bus bridges
- G06F13/4031—Coupling between buses using bus bridges with arbitration
- G06F13/4036—Coupling between buses using bus bridges with arbitration and deadlock prevention
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2205/00—Indexing scheme relating to group G06F5/00; Methods or arrangements for data conversion without changing the order or content of the data handled
- G06F2205/06—Indexing scheme relating to groups G06F5/06 - G06F5/16
- G06F2205/067—Bidirectional FIFO, i.e. system allowing data transfer in two directions
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2213/00—Indexing scheme relating to interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F2213/0004—Parallel ports, e.g. centronics
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Abstract
An asynchronous interface according to the invention comprises: a transmission circuit that transmits data in one byte, with W bit data (W is an integer of 1 or more) as one byte, and transmits a REQ signal whose value differs by one bit per one byte of data transmitted; a reception circuit including a reception buffer whose reception buffer byte count is n (n is an integer of 4 or more), the reception circuit receiving data in one byte and transmitting an ACK signal whose value differs by one bit per reception of one byte of data; a data signal line whose bit width is W and which transmits the data from the transmitting circuit to the receiving circuit; REQ signal line, bit width log2(n) or more, and transmitting the REQ signal from the transmission circuit to the reception circuit; and ACK signal line whose bit width is log2(n) and transmitting the ACK signal from the receiving circuit to the transmitting circuit.
Description
Technical Field
The present invention relates to an asynchronous interface using a handshake protocol.
Background
In data transmission between asynchronous blocks using a handshake protocol, the handshake constitutes a reciprocal communication of each data transmission. Therefore, the long transmission distance and the large transmission delay of the handshake cause a decrease in the maximum transmission rate. PTL1 and PTL2, and NPL1 propose methods of preventing such a decrease in transmission rate. For example, as a method for preventing a decrease in the transmission rate, the following methods are known:
the method comprises the following steps: in a simple handshaking system, multiple data signal lines are used in parallel. For example, the configuration described in the lower part of fig. 1 using a plurality of NPLs 1.
The method 2 comprises the following steps: asynchronous first-in first-out (FIFO) of a bucket brigade system is uniformly configured between asynchronous blocks (see the upper part of fig. 1 of NPL1 and PTL 2).
The method 3 comprises the following steps: two FIFOs are used to hide the transfer delay of the handshake (see fig. 6 of NPL1 and PTL 1).
[ list of cited documents ]
[ patent document ]
PTL 1: description of the US7417993 patent
PTL 2: description of U.S. patent application publication US2014/0064096
[ non-patent document ]
NPL 1: IEEE Asynchronous Signal (SAS) Protocol for Asynchronous Handshake Communication with Wireless Delay Overhead, IEEE Asynchronous Circuit and System (ASYNC), IEEE 19th International conference on topic of 2013, 19th to 22 th month in 2013(page 107-
Disclosure of Invention
However, the number of wirings and circuits of the method 1 as described above may increase in proportion to the number of parallel data signal lines.
As in the method 2 described above, in order to keep the timing constraint, a large number of design man-hours are required to achieve optimal circuit arrangement and wiring. Moreover, because the number of FIFO stages is small relative to the transmission distance, the handshake communication distance in the FIFO sections becomes longer. This results in a reduction in the maximum transmission rate.
The method 3 as described above requires two FIFO circuits, which results in an increase in the number of circuits. Moreover, since both FIFOs are affected by cosmic rays (α rays), for example, and are brought into a state of inconsistency between the transmission side and the reception side, both the transmission side and the reception side are brought into a standby state. Then, a stall state of the handshake occurs, which results in the possibility that the handshake will not be restored to normal operation. For example, let us assume the case of animated data transmission. The effect of errors occurring on the data side is counteracted by the periodic updating of the image frames. From the user's point of view, such errors result only in transient deformations of the image. However, the occurrence of the transmission control pause causes a serious situation such as image stop. In many cases, recovery must require resetting the device or turning the power on again.
Therefore, it is desirable to provide an asynchronous interface that can prevent a decrease in the transmission rate.
An asynchronous interface according to one embodiment of the present invention includes a transmission circuit, a reception circuit, a data signal line, a REQ signal line, and an ACK signal line. The transmission circuit transmits data in one byte, with W bit data (W is an integer of 1 or more) as one byte, and transmits a REQ signal whose value differs by one bit per one byte of data transmitted. The reception circuit includes a reception buffer whose reception buffer byte count is n (n is an integer of 4 or more). The receiving circuit receives data in one byte and transmits an ACK signal whose value differs by one bit per byte of data received. The bit width of the data signal line is W, and the data is transmitted from the transmitting circuit to the receiving circuit. Bit width of the REQ signal line is log2(n) or more, and transmitting the REQ signal from the transmission circuit to the reception circuit. Bit width of the ACK signal line is log2(n) or more, and transmitting the ACK signal from the receiving circuit to the transmitting circuit.
In the asynchronous interface according to an embodiment of the present invention, the transmission circuit transmits data in one byte, with W bits of data as one byte, and transmits the REQ signal whose value differs by one bit per transmission of one byte of data. The receiving circuit includes a receiving buffer whose number of receiving buffer bytes is n. The receiving circuit receives data in one byte and transmits an ACK signal whose value differs by one bit per byte of data received.
According to an asynchronous interface of an embodiment of the present invention, the receiving circuit includes a receiving buffer capable of buffering a plurality of bytes. This provides a configuration that allows data transfer to be free of the rate limit of the time taken for handshaking. Thus, a decrease in the transmission rate can be prevented.
It should be noted that the effects of the present invention are not necessarily limited to the effects described above, and may include any of the effects described herein.
Drawings
Fig. 1 is a circuit diagram illustrating one configuration example of an asynchronous interface according to a first embodiment of the present invention.
Fig. 2 is an explanatory diagram illustrating one example of the conversion of the signal values of the REQ signal and the ACK signal using gray codes.
Fig. 3 is a circuit diagram illustrating one configuration example of an asynchronous interface according to a second embodiment of the present invention.
Fig. 4 is a timing chart of the transmission circuit side in the asynchronous interface according to the second embodiment.
Fig. 5 is a timing chart of the reception circuit side in the asynchronous interface according to the second embodiment.
Detailed Description
Some embodiments of the present invention are specifically described below with reference to the accompanying drawings. It should be noted that the description is made in the following order.
First embodiment of transmitter (FIGS. 1 and 2)
1.1 configuration
1.2 operating
1.3 Effect
Second embodiment of the capsule (FIGS. 3 to 5)
2.1 configuration
2.2 operating
2.3 Effect
3. Other embodiments
[ first embodiment of force generating tool ]
1.1 configuration
Fig. 1 illustrates one configuration of an asynchronous interface according to a first embodiment of the present invention. This embodiment relates to an asynchronous interface that transmits DATA (DATA) through a handshake protocol using a REQ (request) signal and an ACK (acknowledge) signal.
The asynchronous interface according to this embodiment includes a transmission circuit Tx, a reception circuit Rx, and signal lines connecting them. The transmission circuit Tx transmits data. The reception circuit Rx receives data. The signal lines include a data signal line 11 and a handshake line. The data signal line 11 transmits data. The handshake lines include a REQ signal line 12 and an ACK signal line 13. The REQ signal line 12 transmits a REQ signal. The ACK signal line 13 transmits an ACK signal.
The transmission circuit Tx receives transmission data WDATA and a transmission request signal WVALID from the outside, and transmits data to the reception circuit Rx according to a handshake protocol using a REQ signal and an ACK signal. The transmission circuit Tx includes a D-type flip-flop (DFF)20, DFFs 21 and 22, a transmission control circuit 23, and a gray code counter 24.
Transmission data WDATA is supplied from the outside to the D terminal of DFF 20. The data transmitted to the reception circuit Rx is output from the Q terminal of the DFF 20. The transmission clock signal WCLK is supplied to the CK terminals of the DFFs 20, 21, and 22. The ACK signal is input to the transmission control circuit 23 through the DFFs 21 and 22.
The transmission clock signal WCLK, the RESET signal RESET, and the transmission request signal WVALID are supplied to the transmission control circuit 23 from the outside. Also, the transmission control circuit 23 outputs a transmission ready signal WREADY to the outside. Further, the ACK signal as the ACKTx signal is supplied to the transmission control circuit 23 through the DFFs 21 and 22. In addition, the transmission control circuit 23 transmits the REQ signal through the gray code counter 24.
The reception circuit Rx includes DFFs 30, 31, and 32, a reception control circuit 33, a gray code counter 34, a decoder 35, a decoder 36, a selector 37, a selector 38, and a reception buffer 39.
The data in the reception buffer 39 is supplied to the D terminal of the DFF 30 through the selector 38. The clock signal is supplied from the reception control circuit 33 to the CK terminal of the DFF 30. The data in the reception buffer 39 is output to the outside through the selector 38 and the DFF 30 as reception data RDATA.
The reception clock signal RCLK, the RESET signal RESET, and the reception ready signal RREADY are supplied to the reception control circuit 33 from the outside. Also, the reception control circuit 33 outputs the reception request signal RVALID to the outside. Further, the REQ signal is supplied to the reception control circuit 33 through the DFF 31 and the DFF 32. Further, the transmission control circuit 23 transmits an ACK signal through the gray code counter 24.
The REQ signal is provided to decoder 35. Decoder 35 outputs the REQ signal to selector 37 as write address signals EN to ENn-1. The selector 37 writes data into the reception buffer 39 in accordance with the write address signals EN to ENn-1.
The ACK signal is provided to decoder 36. The decoder 36 outputs the ACK signal to the selector 38 as a read address signal. The selector 38 reads out the data in the receiving buffer 39 based on the read address signal.
The transmission circuit Tx transmits data of W bits (W is an integer of 1 or more) as one byte. Furthermore, the transmission circuit Tx transmits a REQ signal whose value differs by one bit for each transmission of one byte of data. The transmission circuit Tx transmits the REQ signal n times for n consecutive data transmissions, the value of the REQ signal being different each time.
The reception buffer 39 is a buffer (a buffer in which the number of buffer stages is n) in which the number of reception buffer bytes is n (n is an integer of 4 or more). The reception buffer 39 is composed of, for example, an n × w bit ring buffer. The receiving circuit Rx receives data in one byte and transmits an ACK signal whose value differs by one bit for each byte of data received. The reception circuit Rx transmits the ACK signal n times with respect to n consecutive data receptions, the value of the ACK signal being different each time.
The data signal line 11 is composed of W signal lines (bit width is W), and transfers data from the transmitting circuit Tx to the receiving circuit Rx.
It should be noted that it is preferable that the number of bytes n of the reception buffer is a power of 2 and is equal to or greater than 8. Preferably, each bit width of the REQ signal line 12 and the ACK signal line 13 is log2(n)。
[1.2 operation ]
The asynchronous interface according to the present embodiment is suitable for data transfer in a case where, for example, the signal line is a wide-area wiring, resulting in a transfer delay large enough to exceed the clock period of the reception circuit Rx or the transmission circuit Tx. For example, the asynchronous interface according to the present embodiment is suitable for data transmission in a case where the sum of the signal transfer time of the REQ signal transmitted through the REQ signal line 12 and the signal transfer time of the ACK signal transmitted through the ACK signal line 13 is greater than the minimum period taken for the transmission circuit Tx to transmit data or greater than the minimum period taken for the reception circuit Rx to receive data.
In the case where the clocks of the transmission circuit Tx and the reception circuit Rx are asynchronous, or in the case where the difference or variation in the clock distribution delay is so large that the clocks must be regarded as asynchronous, in order to achieve synchronization, the REQ signal and the ACK signal must be received, for example, by a two-stage shifter of DEF. In addition, there are times involved in the transmission operation and the reception operation, and transmission delays of the REQ signal and the ACK signal between the blocks in the transmission circuit Tx and the reception circuit Rx. The sum of all these delays constitutes the time taken for the handshake of the data transfer of one byte.
In order to suppress a decrease in the transmission rate caused by the time taken for handshaking, it is preferable that the number of receive buffer bytes n is determined so as to satisfy the relationship:
n×Tb≥Ta，
where Ta denotes the time taken for a single handshake, and Tb denotes the larger of the transmission clock period of the transmission circuit Tx and the reception clock period of the reception circuit Rx.
More specifically, Ta represents the time taken for the transmitting circuit Tx to transmit one byte of data and the REQ signal, for the receiving circuit Rx to transmit the ACK signal in response thereto, for the transmitting circuit Tx to receive the ACK signal, and for the transmitting circuit Tx to decide whether or not the next data transfer is possible.
As an example, an operation is described with reference to fig. 2, in which, with the gray code counters 24 and 34, the reception buffer byte number n is 8, and the bit width of the REQ signal line 12 is log of the bit width of the ACK signal line 132(8) The REQ and ACK signals are each allowed to differ by one bit at a time, 3 bits.
For example, as shown in fig. 2, the gray code counters 24 and 34 output 3-bit values clockwise. Gray code counters 24 and 34 only change the REQ signal and the ACK signal by one bit per byte transmitted.
If the RESET signal RESET is issued, the transmission control circuit 23 and the reception control circuit 33 perform initialization in the gray code counters 24 and 34, resulting in the value of the REQ signal being 000 that of the ACK signal.
In the case where the transmission request signal WVALID is issued and "the next value of the REQ signal ≠ the value of the ACK signal", the transmission circuit Tx outputs a new piece of data, and in synchronization therewith, updates the REQ signal to the next value. The receiving circuit Rx uses the REQ signal as an address to write data to the receiving buffer 39.
In the case where a pass latch is used for the storage element of the reception buffer 39, it is sufficient to decode the REQ signal by an inverter or a logic gate such as NAND, and input the resultant signal as it is to the enable terminal of the pass latch. In the case where the DFF is used for the storage element of the reception buffer 39, it is also sufficient to decode the REQ signal by an inverter or a logic gate such as NAND, and the resultant signal is input to the clock terminal as it is. In both cases, because the REQ signal changes by one bit, the decoder circuit can be easily designed in which unnecessary whisker pulses do not occur in the decoded signal. Whisker pulsing causes erroneous operation.
In the case where the reception preparation signal RREADY is issued and "the next value of the ACK signal ≠ value of the REQ signal", the reception circuit Rx uses the ACK signal as the read address, and outputs the data in the reception buffer 39 to the outside as reception data RDATA. Further, in synchronization with this, the reception circuit Rx updates the ACK signal to the next value, and thereby notifies the transmission circuit Tx side of the readout completion address.
As described above, the reception circuit Rx uses the REQ signal as a write address, writes the received data to the reception buffer 39 by one byte, and uses the ACK signal as a read address, reading out the data in the reception buffer 39 by one byte. The transmission circuit Tx notifies the reception circuit Rx of the reception time of the data by the REQ signal. The reception circuit Rx writes data into the reception buffer 39 at the timing of the REQ signal. The reception circuit Rx uses the REQ signal and the ACK signal as pointers of the reception buffer 39.
By the operation as described above, even in the case where the ACK signal from the reception circuit Rx side is delayed, the transmission circuit Tx side can perform transmission without waiting for the ACK signal according to the number of dummy bytes in the reception buffer 39 that guarantees this state.
Now, generally, as a synchronous technique of an asynchronous signal, a shifter by DFF using a clock of a receiving side is often used. By the DFF being transmitted with respect to a plurality of bits, depending on the clock timing, there is a possibility that the receiving side receives a value which is not desired by the transmitting side and performs an erroneous operation. For example, in the case where the transmitting side changes the signal from 000 to 111, there is a possibility that the receiving side samples the signal in the course of the change and receives values such as 010 and 110. However, in this embodiment, since the variation is limited to one bit at a time, even in the case where synchronization of the REQ signal and the ACK signal of multiple bits is performed by the shift operation of the DFF, no erroneous operation occurs in the logic circuit at the subsequent stage. Also, at the time of writing data to the reception buffer 39 by using the signal decoded from the REQ signal on the reception circuit Rx side, since one bit is changed, even in the case where the write control signal of data is generated only by a logic gate other than the DFF, erroneous operation can be prevented.
[1.3 Effect ]
As described above, according to the embodiment, the reception circuit Rx includes the reception buffer 39 that can buffer a plurality of bytes. The configuration thus provided allows data transfer to be rate limited by the time taken for handshaking. Thus, a decrease in the transmission rate can be prevented.
In this embodiment, the receive buffer word count is n, and the bit width of each of the REQ signal line 12 and the ACK signal line 13 is log2(n) or more. Also, the REQ signal and the ACK signal are used as pointers for writing or reading out the reception buffer 39. Thus, the comparison of the values of the REQ signal and the ACK signal may determine whether a next data transmission is possible. Therefore, when data is transferred between asynchronous blocks, even if there is a long signal transfer time between blocks, the reception buffer word count n is determined so as to satisfy the relationship of n × Tb ≧ Ta as described above, and high-speed data transfer can be performed without being limited by the rate of time taken for handshaking.
Furthermore, according to the present embodiment, even in the case where the sum of the signal transmission time of the REQ signal transmitted through the REQ signal line 12 and the signal transmission time of the ACK signal transmitted through the ACK signal line 13 is larger than the minimum period (minimum data transmission period) taken for the transmission circuit Tx to transmit data or larger than the minimum period taken for the reception circuit Rx to receive data, it is possible to prevent a decrease in the transmission rate. Here, let us consider a case in which at least the receiving circuit Rx is an asynchronous circuit that does not use a clock, or the receiving circuit Rx operates with a clock period that is sufficiently small relative to the minimum period that the transmitting circuit Tx takes to transfer data. In such circuits, a DFF shifter for synchronization of handshake signals is unnecessary or the delay for synchronization with the DFF shifter becomes small with respect to the transmission period. Since the transmission delay of the REQ signal and the ACK signal becomes small in such a circuit, there is a case where even in the case of transmission by simple handshake in which the number of signal lines of the REQ signal line 12 and the number of signal lines of the ACK signal line 13 are each one, the transmission rate is not limited by the rate of time taken for handshake. However, in the case where the reception circuit Rx performs transmission under the above-described conditions without using an asynchronous circuit of a clock, or in the case where the reception circuit Rx performs transmission by simple handshake with a clock cycle operation sufficiently small relative to the minimum data transmission cycle of the transmission circuit Tx, a reduction in the transmission rate still occurs. Even in this case, according to the present embodiment, a decrease in the transmission rate can be prevented.
So that the bit widths of the REQ signal line 12 and the ACK signal line 13 are log, respectively2(n) and makes the number of DFFs in the sequential circuit also log2(n) the sequential circuit may be made a circuit without extra states, i.e. states not used in normal operation. The timing circuit generates the values of the REQ signal and the ACK signal. Thus, in this embodiment, the handshake control is not brought into a stalled state even in the event of a soft error, for example, due to a cosmic ray. This brings the advantage of a highly reliable system such as medical devices and space exploration related devices. Furthermore, consumer devices also have a high reliability in the case of great impact from cosmic rays, for example when used on aircraft or on mountains.
It should be noted that the effects described herein are merely examples. The effects of the present invention are not limited to the effects described herein. The effects of the present invention include effects other than those described herein. The same is true for the other embodiments described below.
[2. second embodiment ]
A second embodiment of the present invention is described below. In the following, description is appropriately omitted with respect to components having similar configurations and actions to those of the first embodiment described above.
[2.1 configuration ]
Fig. 3 illustrates one configuration example of an asynchronous interface according to a second embodiment of the present invention.
The asynchronous interface according to the present embodiment includes two data signal lines 11A and 11B. Each of the two data signal lines 11A and 11B is constituted by W signal lines (the bit width is W). The two DATA signal lines 11A and 11B each transmit DATA (DATA0) and DATA (DATA 1).
Instead of the DFF 20 in the configuration of fig. 1, the transmission circuit Tx includes a DFF 20A and a DFF 20B. Also, the transmission circuit Tx includes not only the configuration of fig. 1 but also the decoder 25.
Transmission data WDATA from the outside is supplied to the D terminals of DFFs 20A and 20B. A control signal based on the REQ signal is supplied to the EN terminals of the DFFs 20A and 20B through the decoder 25.
Otherwise, the configuration is substantially similar to that of fig. 1.
[2.2 operations ]
Fig. 4 illustrates a timing chart on the Tx side of the transmission circuit of the present embodiment. Fig. 5 illustrates a timing chart on the Rx side of the reception circuit of the present embodiment.
In the case of a high clock frequency, or in the case where the transmission delay deviation is large and the difference between the transmission delays of the data and REQ signals causes a failure in normally receiving data on the side of the reception circuit Rx, the number of data signal lines 11 can be increased, thereby securing a wider data stabilization period.
In the present embodiment, as shown in fig. 3 and 4, the transmission circuit Tx distributes data of a plurality of bytes to the two data signal lines 11A and 11B in one byte manner, and transmits the data of a plurality of bytes so that transmission timings are different from each other. At this moment, the transmitting circuit Tx alternately distributes the DATA0 and the DATA1 to the two DATA signal lines 11A and 11B according to the value of the REQ signal, and transmits the DATA0 and the DATA 1. Therefore, as shown in fig. 3, the data stabilization period can be made Tclk × 2, where Tclk is a clock period of the transmission circuit Tx. The allowable delay difference can be extended to a clock period of about ± Tclk.
It should be noted that, in the present embodiment, the case of two data signal lines 11A and 11B (two systems of data signal lines) is described. However, three or more systems of data signal lines may be provided. Data can be distributed to and transmitted from three or more data signal lines of the system.
[2.3 Effect ]
In order to secure data reception by the reception circuit Rx, it is difficult to sufficiently reduce the relative difference between the data transmission and the delay of the transmission of the REQ signal, and the present embodiment is effective in this case. Increasing the number of data signal lines 11, distributing data according to the value of the REQ signal on the Tx side of the transmission circuit, and latching data according to the value of the REQ signal on the Rx side of the reception circuit can increase the allowable range of the relative difference between the delays. The timing constraints can be alleviated by adding only logic to decode the REQ signal and select the transmit data line.
[3. other examples ]
The technique according to the present invention is not limited to the description of the above exemplary embodiments, and may be modified in various ways.
For example, the present technology may be configured as follows:
(1)
an asynchronous interface, comprising:
a transmission circuit that transmits data in one byte, with W-bit data (W is an integer of 1 or more) as one byte, and transmits a REQ signal whose value differs by one bit per one byte of the data transmitted;
a reception circuit including a reception buffer whose reception buffer byte count is n (n is an integer of 4 or more), the reception circuit receiving data in one byte, and transmitting an ACK signal whose value differs by one bit per reception of one byte of data;
a data signal line having a bit width of W, the data signal line transmitting the data from the transmitting circuit to the receiving circuit;
REQ signal line, bit width log2(n) or more, the REQ signal line transmitting the REQ signal from the transmission circuit to the reception circuit; and
ACK signal line whose bit width is log2(n) or more, the ACK signal line transmits the ACK signal from the receiving circuit to the transmitting circuit.
(2)
The asynchronous interface according to (1), wherein,
the transmission circuit transmits the REQ signal n times with respect to n consecutive data transmissions, the value of the REQ signal being different each time, an
The receiving circuit receives the ACK signal n times with respect to n consecutive data receptions, the value of the ACK signal being different each time.
(3)
The asynchronous interface according to (1) or (2), wherein,
the reception circuit writes the received data in the reception buffer by one byte using the REQ signal as a write address, and reads out the data in the reception buffer by one byte using the ACK signal as a read address.
(4)
The asynchronous interface according to any one of (1) to (3), wherein,
the sum of the signal transmission time of the REQ signal transmitted through the REQ signal line and the signal transmission time of the ACK signal transmitted through the ACK signal line is greater than the minimum period taken by the transmission circuit to transmit the data or greater than the minimum period taken by the reception circuit to receive the data.
(5)
The asynchronous interface according to any one of (1) to (4), wherein,
ta represents the time it takes for the transmitting circuit to transmit one byte of the data and the REQ signal, for the receiving circuit to transmit the ACK signal in response thereto, for the transmitting circuit to receive the ACK signal, and for the transmitting circuit to decide whether to perform the next data transmission,
tb denotes the larger period of the transmission clock period of the transmission circuit and the reception clock period of the reception circuit, and satisfies the following relationship,
n×Tb≥Ta。
(6)
the asynchronous interface according to any one of (1) to (5), wherein the data signal line having the bit width of one byte is provided in two or more systems, and
the transmission circuit allocates a plurality of bytes of the data to the data signal lines of the two or more systems in one byte, and transmits the plurality of bytes of the data so that transmission timings are different from each other.
(7)
The asynchronous interface according to any one of (1) to (6), wherein,
the receive buffer byte number n is a power of 2 and is equal to or greater than 8, and,
the bit width of each of the REQ signal lines and the ACK signal lines is log2(n)。
This application claims the benefit of japanese priority patent application JP2015-069109, filed on 2015, 3/30, which is incorporated herein by reference in its entirety.
It will be appreciated by those skilled in the art that various modifications, combinations, sub-combinations, and alternatives may be made in accordance with design requirements and other factors within the scope of the appended claims and their equivalents.
Claims (7)
1. An asynchronous interface, comprising:
a transmission circuit that transmits data in one byte, W bit data as one byte, W being an integer of 1 or more, and transmits a request signal whose value differs by one bit per transmission of the data of one byte;
a receiving circuit including a receiving buffer whose receiving buffer byte count is n, n being an integer of 4 or more, the receiving circuit receiving data in one byte, and transmitting an acknowledge signal whose value differs by one bit per reception of one byte of data;
a data signal line having a bit width of W, the data signal line transmitting the data from the transmitting circuit to the receiving circuit;
request signal line whose bit width is log2(n) or more, the request signal line transmits the request signal from the transmitting circuit to the receiving circuit; and
confirming signal line whose bit width is log2(n) or more, the acknowledgement signal line transmits the acknowledgement signal from the receive circuit to the transmit circuit.
2. The asynchronous interface of claim 1 wherein,
the transmission circuit transmits the request signal n times with respect to n consecutive data transmissions, the value of the request signal being different each time, an
The receiving circuit receives the acknowledgement signal n times with respect to n consecutive data receptions, the value of the acknowledgement signal being different each time.
3. The asynchronous interface of claim 1 wherein,
the receiving circuit writes the received data in the receiving buffer by one byte using the request signal as a write address, and reads the data in the receiving buffer by one byte using the acknowledge signal as a read address.
4. The asynchronous interface of claim 1 wherein,
the sum of the signal transfer time of the request signal transferred through the request signal line and the signal transfer time of the acknowledge signal transferred through the acknowledge signal line is larger than the minimum period taken by the transmitting circuit to transmit the data or larger than the minimum period taken by the receiving circuit to receive the data.
5. The asynchronous interface of claim 4 wherein,
ta represents the time it takes for the transmit circuit to transmit one byte of the data and the request signal, for the receive circuit to transmit the acknowledgement signal in response thereto, for the transmit circuit to receive the acknowledgement signal, and for the transmit circuit to decide whether to proceed with the next data transfer,
tb denotes the larger period of the transmission clock period of the transmission circuit and the reception clock period of the reception circuit, and satisfies the following relationship,
n×Tb≥Ta。
6. the asynchronous interface of claim 1 wherein,
said data signal line having said bit width of one byte is provided in a system of two or more, an
The transmission circuit allocates a plurality of bytes of the data to the data signal lines of the two or more systems in one byte, and transmits the plurality of bytes of the data so that transmission timings are different from each other.
7. The asynchronous interface of claim 1 wherein,
the receive buffer byte number n is a power of 2 and is equal to or greater than 8, and,
the bit width of each of the request signal line and the acknowledge signal line is log2(n)。
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| JP2015-069109 | 2015-03-30 | ||
| JP2015069109 | 2015-03-30 | ||
| PCT/JP2016/054808 WO2016158063A1 (en) | 2015-03-30 | 2016-02-19 | Asynchronous interface |
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| CN107430578A (en) | 2017-12-01 |
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| JPWO2016158063A1 (en) | 2018-01-25 |
| US20180074991A1 (en) | 2018-03-15 |
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